Kivy如何在函数中访问小部件，没有KV只是python代码

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout

class MyApp(App):
    def build(self):
        layout = BoxLayout(orientation='vertical')
        button = Button(text='Click Me')
        button.bind(on_press=self.button_pressed)
        layout.add_widget(button)
        return layout

    def button_pressed(self, instance):
        # 在这个函数中访问小部件
        print("Button pressed!")
        print("Button text:", instance.text)

if __name__ == '__main__':
    MyApp().run()